ALL AUTOCARS

Terminal: place where a current-conducting wire is attached.

Spline: hollow channel.

Resistance: device that controls the strength of the current.

Ground electrode: current device that unites the electrodes.

Spark plug gap: space separating the current conductors.

Center electrode: central current conductor.

Gasket: spot where two part join together.

Spark plug body: metal part of the spark plug.

Hex nut: hexagonal piece of metal used to screw in a spark plug.

PROBLEM
A typical spark plug requires 5000 to 25000 volts from the ignition coil before it will fire. The exact firing voltage depends on the plug gap (the wider the gap, the higher the voltage required) and the electrode condition (wear increase voltage requirements) and the operating temperature (a cold plug requires more voltage to fire than a hot one). The spark must occur to coincide with the piston position as it approaches top dead center on its compression stroke. If the spark occurs too soon (over advanced timing), cylinder pressures rise too quickly and peak too early in the cycle resulting in power loss. This can also cause "detonation" to occur. If the spark occurs too late, cylinder pressures peak too late in the cycle also resulting in a loss of power. The by- product of increased compression is the increase in cylinder temperatures. These high temperatures must be managed by suitable plug designs.

HEAT RANGE

The "heat range" of a spark plug determines how hot the plug runs during normal operation. If the heat range is correctly matched to the engine application, the plug will run hot enough under normal driving conditions to burn off fouling deposits before they can cause problems. Likewise, the plug will not get too hot and become a source of ignition causing engine-damaging pre-ignition and detonation. If the heat range is too cool for the application, though, fouling deposits may build up faster than they are burned off. For this reason, always follow the vehicle manufacturer or plug supplier heat range recommendations when selecting a spark plug for a particular application. Two spark plugs may appear to be identical on the outside but have entirely different heat ranges.

Many of today's spark plugs have a very broad heat range because the plug manufacturer uses a copper core or platinum center electrode. Copper is an excellent conductor of heat, so the insulator can be designed to run hotter and burn off fouling deposits without it getting too hot under increased load to cause pre-ignition or detonation. A solid platinum center electrode will also carry heat away from the tip, but not if the electrode only has a platinum tip.

PERFORMANCE ENGINE

Modified engines like nitrous oxide injection, smaller-chambered and free-flowing cylinder heads, engines with high compression ratio or force induction usually necessitate changing plug types or heat ranges. Specific electrode/tip combinations, electrode materials and colder heat ranges to remove the heat can provide measurable gains in power. For example: running extreme boost (more than 18 psi), a big shot of nitrous (more than 100 hp) or high compression (more than 11:1) the cold plug must be selected and plug gaps should be adjusted smaller to ensure proper ignitability with a much denser air;/fuel mixture. The smaller gap withe stock ignition loses a little power but this can mitigate problems until you change to a better ignition coil.

For every 75 to 100 hp you add to your engine, you may go to the next colder step. A hotter heat range is not usually recommended except when severe oil or fuel fouling is occurring. The difference from one full heat range to the next is the ability to remove 70 degrees C to 100 degrees C from the combustion chamber.

COLD and HOT PLUG

A "hot plug" has longer porcelain insulator nose which exposes more surface area to dissipate heat more slowly. The plugs electrodes must stay hot enough to burn away and self-clean fouling carbon deposits. This keeps the plug temperature higher overall which is ideal for low speed and city driving conditions. However, a plug that is too "hot" can overheat, also causing power loss, detonation, pre-ignition and possible engine damage.

A "cold" plug can be identified by a shorter porcelain insulator nose that minimizes the amount of surface area exposed to the combustion gases therefore having a shorter path to conduct heat out of the electrode and out of the cylinder chamber quickly. For engines with increased cylinder pressures, higher temperatures and greater horsepower, switching to a slightly colder plug can minimize the risk of pre-ignition and detonation if the plug becomes too hot. However the spark plug must achieve its "self-cleaning" temperature where it can burn off fuel and carbon deposits.

An exhaust manifold or header collects the exhaust gases from multiple
cylinders into one pipe. Among all of the after market tuning products, exhaust extractors
are on the top of the list amongst the most cost effective power improvement solutions.

Exhaust manifolds are generally and traditionally simple cast iron units which collect
engine exhaust and deliver it to the exhaust pipe. However, when greater performance is
required, this restrictive tube is often replaced with individual extractor which are tuned for low restriction and improved
performance. There are two distinct types of extractors. Four into two then into one (4-2
-1) and four into one (4-1). The different between these two are 4-1 design is mainly
suited to engines that spend most of their lives revving at high RPM in track circuits.
The 4-2-1 design is more suitable for road use, giving a good usable power band across a
wider RPM range.

Tuned Length Extractors
They work exceptionally well in the high rev range and ideal for drag racing.

TRI-Y Design Extractors
The most common design of extractors, Tri-y extractors give you more power in the
rev range that you use on the street. As a general rule you should
anticipate an increase in power, performance and fuel economy of around 10% under normal
driving conditions.

Tools and Supplies

1. Spark Plugs
2. Socket set with spark plug socket or spark plug wrench
   
3. Torque wrench
4. Rag or paper towels
5. Penetrating oil
6. Wire feeler gauge and gapping tool

Let's start...

Firstly, mark each ignition wire and corresponding spark plug location with a number on a piece of masking tape.

Secondly, we need to disconnect the ignition wire or coil packs. Pull the plug cable boot straight out to disconnect each cable. On models with individual ignition coil packs, pull the coil pack straight out. Some engines may require you to remove the top cover in order to access the plugs.


Then, it is the time to remove the spark plugs. If you can reach the base of the spark plug, apply penetrating oil where it seats to the cylinder head. This will protect the threading in the cylinder head. remove each spark plug and its metal washer with a spark plug wrench or spark plug socket.







The forth step is to inspect the old spark plug that just taken out. For more information regarding spark plug, please refer to Spark Plug Firing End Analysis.. After that, remove old spark plug washers from the spark plug holes.







Next is to set spark plug gap. Using a wire feeler gauge, check the gap between the electrodes to the correct clearance. Carefully bend the outer electrode as required to feel a slight drag on the wire gage.

CONDITION	ACTION
Engine runs rough or will not run	Check the ignition wires or coil packs for proper connection to the spark plugs. Check the ignition wires or coil packs for proper connection to cylinders.
There is a loud hissing noise	One or more spark plugs have been improperly tightened – re-check. One or more spark plugs may have double washers – re-check. Spark plug may have been cross-threaded – re-install.
There is a very loud clicking or tapping noise	A foreign object may have fallen into one of the cylinders. If the noise persists, DO NOT DRIVE THE VEHICLE – have it towed to your Service Department for diagnosis and repair.
Engine has poor performance, runs hot or overheats	The incorrect plugs may have been installed – re-check. The spark plug gap may be incorrect – re-check. One or more ignition wires may have been damaged. DO NOT DRIVE THE VEHICLE if the engine overheats.

Audi R8. The Audi R8 is top cars of 2008 a mid-engined sports car released by the German automaker Audi. But Audi stopped the production of the first version and substituted it with the 2007 model, using some of lamborghini features. First appearance of the car was in 2005, the first successor. Audi announced in 2005 that the name of the successful Audi R8 race car would be used for a new road car in 2007, the Audi R8, based on the Audi Le Mans Quattro concept car, which was based on the earlier Audi RSQ concept vehicle. The R8 was officially launched at the Paris Auto Show on 30 September 2006.

Nissan GT-R one of top new cars of 2008. Next generation 2009 Nissan GT-R performance car, previewed as the GT-R PROTO concept car. At the official Nissan GTR web site, is coming to North America in 2008, previously known as the Skyline GT-R.

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